The present invention relates to a method and an apparatus for adjusting the alignment of a beam characteristic of a distance sensor. In particular, the present invention relates to an adjustment of the alignment of a beam characteristic of a proximity radar that is mounted in or on a motor vehicle, for example in the context of an automatic speed regulation system or a collision detector. The present invention can be used for the adjustment of all distance sensors that are based on the transmission and reception of electromagnetic or other waves.
An apparatus for adjusting a directional antenna of a radar proximity warning device of a vehicle is described in German Patent No. 42 01 214. The apparatus described in this German patent provides that the directional antenna is joined to an adjustment headlight to form a rigid unit that is displaceably attached to the vehicle by way of a displacement board, and this unit is adjustable by aligning the optical axis of the cone of light of the adjustment headlight using a vehicle-related optical detection device. The adjustment accuracy of the radar proximity warning device thus depends on the accuracy with which the cone of light of the adjustment headlight is adjusted. The proximity warning radar is not itself directly used for the adjustment.
It is also known, as described in this German patent, to adjust radar proximity warning devices with the aid of a commercially available microwave measurement device that detects the ray bundle emitted by the directional antenna. Measurement devices of this kind are, however, expensive, complex, difficult to operate, and are not yet part of the normal equipment of a motor vehicle repair shop.
Japanese Patent Application No. 08-327722 describes an apparatus for an automatic adjustment of the optical axis of a radar beam on the longitudinal vehicle axis (i.e., a central line). A beam is emitted from a radar unit toward a detection element that is located at a predetermined position in front of the motor vehicle. The reflected beams are sensed by a detection unit. A control unit then controls the radar unit in such a way that the optical axis of the radar coincides with the longitudinal vehicle axis.
The present invention provides a method and an apparatus with which a distance sensor, in particular on a motor vehicle, can be adjusted with respect to a reference axis in a simple, economical, and precise manner. xe2x80x9cAdjustment of a distance sensorxe2x80x9d means in this context, more specifically, the adjustment of the alignment of the beam characteristic of the distance sensor.
The advantages of the present invention provides e.g., the fact that adjustment of the distance sensor is accomplished without special, expensive, and difficult-to-operate measurement devices, in particular without special microwave devices. The apparatus and the method according to the present invention are accordingly very robust and very easy to operate and perform. This also applies in particular to persons who do not have specific knowledge of microwaves or of the particular technology corresponding to a distance sensor that is being used. The apparatus according to the present invention can be manufactured with little outlay from apparatuses known in the motor vehicle sector, in particular from a headlight aiming device or an axle alignment stand. All that is necessary therewith is to attach a reflector that is suitable as a target object for the distance sensor. One advantage as compared to the apparatus described in German Patent No. 42 01 214 is that the adjustment accuracy of the distance sensor is determined by the resolution capability of the distance sensor itself, and not by a headlight that is completely independent of it. This ensures that the adjustment accuracy corresponds exactly and optimally to the particular distance sensor being used. A further advantage of the method according to the present invention is that a functional check of the distance sensor is performed simultaneously with the adjustment.